JP2018075527A - Soil purification system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a soil purification system capable of impregnating injection liquid uniformly into soil.SOLUTION: A soil purification system 10 has a water injection layer 20 provided on the surface of soil G or in the soil G, and formed flatly of a material having higher water permeability than the soil G, an injection facility 30 for impregnating injection liquid into the soil G from the water injection layer 20 by injecting the injection liquid containing a material for decomposing a contaminant into the water injection layer 20, and a withdrawal wellhole 40 for pumping underground water containing the injection liquid from the soil G.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a soil purification system.

  Patent Document 1 listed below discloses a method for purifying contaminated soil by adding a nutrient for a microorganism that decomposes pollutants to groundwater pumped from a pumping well and allowing the groundwater to penetrate from the water injection well into the contaminated soil. .

JP, 2015-160175, A

  In the method for purifying contaminated soil of Patent Document 1 described above, groundwater added with nutrients is permeated into the contaminated soil from the water injection well. Infusion) is difficult.

  In view of the above facts, an object of the present invention is to provide a soil remediation system capable of evenly infiltrating an injection solution into soil.

  The soil purification system of Claim 1 is provided in the surface of soil or in the soil, the water injection layer formed in the surface by the material whose water permeability is higher than the said soil, and the substance for decomposing | disassembling a pollutant into the said water injection layer And a pumping facility for pumping groundwater containing the injected solution from the soil.

  In the soil purification system according to the first aspect, since the injection solution is injected into the water injection layer having higher water permeability than the soil, the injection solution is likely to penetrate into the water injection layer earlier than the soil infiltration into the soil. Since this water injection layer is formed in a planar shape, the injected liquid permeates through the soil from the water injection layer toward the pumping equipment. For this reason, compared with the case where an injection liquid is made to osmose | permeate into soil from a rod-shaped (linear) water injection well, for example, it is easy to infiltrate an injection liquid into soil equally.

  In the soil purification system according to claim 2, the water injection layer is provided on a surface of the soil, and the pumping equipment is a pumping well.

  In the soil purification system according to the second aspect, since the water injection layer is provided on the surface of the soil, the injected liquid penetrates into the soil by gravity. This eliminates the need for a water injection well for infiltrating the injection solution. Moreover, since the pumping facility is a pumping well, it is possible to pump water from a deep location in the soil. For this reason, penetration of the injected liquid by gravity can be promoted.

  In the soil purification system according to claim 3, a water blocking wall is provided on an outer peripheral portion of the water injection layer.

  In the soil purification system according to the third aspect, since the water blocking wall is provided on the outer peripheral portion of the water injection layer, the injected liquid injected into the water injection layer is unlikely to flow out of the water injection layer. For this reason, it can suppress that an injection liquid flows into the part which does not need to infiltrate an injection liquid, and soil purification efficiency is high.

  According to the soil purification system which concerns on this invention, an injection liquid can be made to osmose | permeate equally to soil.

It is an elevation sectional view showing the soil purification system concerning a 1st embodiment of the present invention. It is a partial expanded vertical sectional view which shows the structure of the water injection layer in the soil purification system which concerns on 1st Embodiment of this invention. It is a partial expanded sectional view which shows the example in which the surface of the soil inclines in the soil purification system which concerns on 1st Embodiment of this invention. (A) is an elevational sectional view showing a procedure for purifying the soil using the soil purification system according to the first embodiment of the present invention, and shows a state in which the soil purification system is constructed above the contaminated soil. ) Shows the state where the groundwater is pumped from the pumping well, (C) shows the state where the injection solution is injected into the water injection layer from the purification device, and (D) continues to inject the injection solution from the purification device into the water injection layer. (E) shows the state where the injection solution is stopped, the injection solution is infiltrated into the soil by gravity, and (F) shows the state where the injection solution has penetrated into the soil. The later state is shown. It is an elevation sectional view showing the soil purification system concerning a 2nd embodiment of the present invention. (A) is a top view which shows the positional relationship of a water injection well, a pumping well, and a water injection layer in the soil purification system which concerns on 3rd Embodiment of this invention, (B) is an elevational sectional view. (A) is an elevational sectional view showing a method for forming a water injection layer in the soil purification system according to the third embodiment of the present invention, and shows a state in which a hole has been drilled in the ground, and (B) is from the hole to the ground. (C) shows a state where a cutout is cut to form a planar channel, and (D) shows a planar water injection layer filled with dredged sand. Shows the state. (A) is an elevational sectional view showing a state in which a plurality of pits are drilled in the ground in the soil purification system according to the third embodiment of the present invention, and a water injection layer formed from each pit is connected, (B) Is a plan view. It is a perspective view which shows the soil purification system which concerns on 4th Embodiment of this invention.

[First Embodiment]
(Soil purification system)
As shown in FIG. 1, the soil purification system 10 according to the first embodiment injects an injection solution into the water injection layer 20 provided on the surface of the soil G and the water injection layer 20, and then passes from the water injection layer 20 to the soil G. An injection facility 30 for infiltrating the injection solution and a pumping well 40 as a pumping facility for pumping up groundwater containing the injection solution from the soil G are provided.

(Injection equipment)
The injection facility 30 includes a purification device 32 that generates an injection solution to be injected into the water injection layer 20, an injection pipe 34 that injects the injection solution generated by the purification device 32 into the water injection layer 20, and before infiltrating into the soil G. And a recovery pipe 36 for recovering a part of the injected liquid. The injection liquid is a liquid containing a substance (decomposing substance) for decomposing the pollutant E contained in the soil G.

  The purification device 32 purifies the groundwater pumped up from the pumping well 40 and adds a decomposition substance to the purified groundwater. As the decomposing substance, a “decomposing microorganism” that biodegrades the pollutant E, a “chemical decomposing agent” that chemically decomposes the pollutant E, an “active agent” that activates biodegradation of the decomposing microorganism, and the like can be used.

  Further, the purifier 32 warms the injected liquid to promote the action of these decomposed substances.

  The injection pipe 34 and the recovery pipe 36 are perforated pipes laid inside the water injection layer 20. The injection liquid is distributed from the purification device 32 to the injection pipe 34 using a pump (not shown). The injection solution is recovered into the purifier 32 using a pump (not shown).

  The recovery pipe 36 is used for recovering the injected liquid injected into the water injection layer 20 and reheating it when the temperature of the injected liquid becomes lower than a predetermined temperature before penetrating into the soil G. It is not always necessary to provide it.

  The amount of water distributed to the injection pipe 34 and the amount recovered from the recovery pipe 36 are controlled by a control unit (not shown) provided in the purification device 32. The control unit also receives a signal from a metering sensor (not shown) and controls the amount of groundwater pumped from the pumping well 40.

(Water injection layer)
The water injection layer 20 is formed of a material having higher water permeability than the soil G, and is laid in a planar shape on the ground surface of the soil G in a range covering the pollutant E to be purified. A water blocking wall 50 formed of a non-permeable material is provided around the water injection layer 20, and the injected liquid injected into the water injection layer 20 is difficult to flow out of the water injection layer 20.

  As shown in FIG. 2, the water injection layer 20 has a three-layer structure. The upper layer 22 is formed of crushed stone, the middle layer 24 is formed of gravel, and the lower layer 26 is formed of dredged sand. Since these particle sizes decrease in the order of crushed stone, gravel, and cinnabar, the water permeability coefficient increases in the order of the upper layer 22, the middle layer 24, and the lower layer 26.

  The injection pipe 34 is embedded in the upper layer 22, and the injection liquid injected into the upper layer 22 quickly permeates in the lateral direction inside the upper layer 22, gradually permeates into the middle layer 24 due to gravity, and further into the lower layer 26.

  In addition, the structure of the water injection layer 20 is not restricted to this, It is good also as a structure of 2 layers or less, or a structure of 4 layers or more. In addition, as a material for forming the water injection layer 20, porous concrete, open-cell urethane foam, a molded product obtained by molding a fibrous or mesh-like polyethylene into a mat shape, a composite material in which a nonwoven fabric is pasted on the surface thereof, or the like Can be used. Impurities (such as biofilms) can be filtered by attaching a nonwoven fabric. When a resin material such as urethane foam or polyethylene is used as a material for forming the water injection layer 20, the density of the resin material in the upper layer is made smaller than that in the middle layer or the lower layer.

  In the present embodiment, the ground surface of the soil G is a substantially horizontal surface, and the water injection layer 20 is also laid substantially horizontally, but the embodiment of the present invention is not limited to this. For example, as shown in FIG. 3, when the ground surface has a gradient, the water injection layer 28 along the gradient may be formed. In such a water injection layer 28, the injected injection solution flows along a gradient, so that the injection solution penetrates into the water injection layer 28 compared to the water injection layer 20 (see FIG. 1) laid horizontally. Cheap. For this reason, the pitch of the injection pipe 34 can be increased. The construction labor can be reduced by increasing the pitch of the injection pipes 34.

  In addition, the gradient of the ground surface of the soil G may be created and provided, or a pre-provided one may be used.

  Moreover, in this embodiment, although injection liquid is inject | poured into the water injection layer 20 from the injection pipe 34, embodiment of this invention is not restricted to this. For example, the injection solution may be sprayed onto the water injection layer 20 by installing a sprinkler on the top of the water injection layer 20 or using a hand-held hose.

(Pumping well)
As shown in FIG. 1, the pumping well 40 is a steel pipe having a strainer 42 at the tip, and has a pump (not shown) inside. The strainer 42 is disposed at a position deeper than the pollutant E to be purified, whereby the pumping well 40 can pump groundwater from a position deeper than the pollutant E.

(Function and effect)
The effect | action and effect of the soil purification system 10 which concern on 1st Embodiment are demonstrated with the purification method of the soil G. FIG. In order to purify the soil G using the soil purification system 10 according to the first embodiment, first, as shown in FIG. 4 (A), the water injection layer 20 is formed on the ground surface of the soil G so as to cover the pollutant E. Form and build the injection facility 30 and the pumping well 40.

  Next, as shown in FIG. 4B, groundwater is pumped from the pumping well 40, and the groundwater level H <b> 1 in the soil G where the pollutant E is present is lowered.

  Next, as shown in FIG. 4C, the injection solution is injected from the injection facility 30 into the water injection layer 20. Since the water injection layer 20 is formed of a material having higher water permeability than the soil G, the injected liquid is more likely to penetrate into the water injection layer 20 than the soil G and is diffused in the lateral direction. Thereby, the injection solution diffuses in a planar shape so as to cover the contaminant E from above.

  In addition, the water injection layer 20 has a high permeability coefficient of the upper layer 22 and a low permeability coefficient of the lower layer 26. For this reason, the injection solution can be diffused in a planar shape in the upper layer 22, and the biofilm contained in the injection solution can be filtered out in the lower layer 26.

  Next, as shown in FIG. 4D, the injection solution penetrates into the soil G by continuing the injection of the injection solution from the injection facility 30 to the water injection layer 20. At this time, since the injected solution penetrates from above to below the soil G due to gravity, the injected solution can penetrate into the soil G without using power.

  Further, the injected liquid diffuses in a planar shape inside the water injection layer 20 and penetrates into the soil G evenly. For this reason, the injection liquid can pass through the entire part including the contaminant E in the soil G.

  Furthermore, a water blocking wall 50 made of a non-permeable material is provided around the water injection layer 20 so that the injected liquid does not easily flow out of the water injection layer 20 (outside in the lateral direction). For this reason, it can suppress that an injection liquid diffuses in the part which does not need to make an injection liquid osmose | permeate.

  The water blocking wall 50 is not necessarily provided. Even if the water blocking wall 50 is not provided, the injected liquid can be diffused in a planar shape. Alternatively, the water blocking wall 20 may be arranged in a lattice shape inside the water injection layer 20 to form the subdivided water injection layer 20. In this way, when the pollutant E is irregularly distributed, it can be efficiently purified by injecting the injection liquid into a part of the subdivided water injection layer.

  Next, as shown in FIG. 4 (E), the injection of the injection solution from the injection facility 30 to the water injection layer 20 is stopped, and the injection solution is permeated into the soil G containing the contaminant E by gravity.

  Next, as shown in FIG. 4 (F), when the injected solution passes through the part containing the pollutant E and the concentration of the decomposition material in the groundwater becomes lower than a predetermined value, the groundwater is discharged from the pumping well 40. Pump up the water. The concentration of decomposed substances is measured using groundwater collected from a pumping well or groundwater collected from a separate observation well.

  Note that the criterion for pumping groundwater from the pumping well 40 is not limited to the concentration of the decomposition substance, and may be the temperature of the groundwater or the soil G, for example. When the temperature of the groundwater or soil G becomes lower than the predetermined value, the groundwater is pumped up, the pumped-up groundwater is purified, a decomposition substance is added to generate an injection solution, and the heated injection solution is infiltrated into the soil G. . The temperature of the groundwater can be measured by a thermocouple installed inside the pumping well, and the temperature of the soil G can be measured by a thermocouple embedded in the soil G.

  Moreover, you may use both the density | concentration of a decomposition substance and the temperature of groundwater (or soil G) as a judgment reference | standard which pumps up groundwater from the pumping well 40. FIG. In this case, the groundwater is pumped when either the concentration or temperature falls below a predetermined value. Note that the “predetermined value” of the concentration and temperature, which are used as an index for starting pumping, is a threshold at which the activity of the degradation substance decreases when the value falls below that value.

[Second Embodiment]
(Coating layer)
As shown in FIG. 5, in the soil purification system 12 according to the second embodiment, a coating layer 52 is provided on the upper part of the water injection layer 20. The covering layer 52 is formed of a concrete panel and is formed by laying on the upper part of the water injection layer 20. Since the concrete panel has low water permeability as compared with the soil G, it is difficult for rainwater to be mixed with the injected liquid injected into the water injection layer 20. For this reason, it can suppress that the density | concentration of a decomposition | disassembly substance becomes low or the temperature of an injection liquid becomes low. Moreover, it can suppress that an injection liquid volatilizes. For this reason, the density | concentration of the decomposition substance in an injection liquid and the temperature of an injection liquid can be maintained at an appropriate value.

  In addition, as a material for forming the covering layer 52, a sheet made of rubber or PVC, asphalt roofing, or the like can be used in addition to a concrete panel. Since these materials also have low water permeability compared to the soil G, it is possible to prevent the rainwater from being mixed into the injection liquid.

  Moreover, in this embodiment, in order to suppress that rainwater mixes with an injection liquid, the coating layer 52 is provided, However, Embodiment of this invention is not restricted to this. For example, the coating layer 52 may be provided in order to make the injection liquid less susceptible to the outside air temperature. In this case, for example, the coating layer 52 is formed of a heat insulating material such as styrene foam, thereby suppressing the heated injection liquid from being cooled by outside air in winter.

  In addition, since polystyrene foam is a foam of a closed cell, it also has a water-stopping property. For this reason, a polystyrene foam can also be used in order to suppress that rainwater mixes with an injection liquid. Thus, the covering layer 52 may be provided for a plurality of purposes. For example, because concrete has a large heat capacity, the concrete panel mentioned above has the purpose of suppressing the mixing of rainwater with the injected liquid, and also reduces the heating energy at night by storing solar heat during the day and dissipating it at night. Can be used for the purpose.

[Third Embodiment]
As shown in FIG. 6B, in the soil G in the third embodiment, a contaminated layer G2 is formed at a position sandwiched between clay layers G1. The clay layer G1 has low water permeability, and it is difficult to infiltrate the injection solution from above.

  Therefore, in the soil purification system 14 according to the third embodiment, the water injection layer 60 formed in a planar shape is formed inside the soil G and above the contaminated layer G2. The water injection layer 60 is formed of crushed stone, gravel, dredged sand, etc., and has a higher water permeability coefficient than the clay layer G1 and the contaminated layer G2.

  The injection facility 70 in the soil purification system 14 includes a water injection well 74 for injecting the injection liquid into the water injection layer 60 instead of the injection pipe 34 (see FIG. 1) in the first embodiment. The tip of the water injection well 74 reaches the contaminated layer G2, and a discharge port (not shown) is provided at a portion in contact with the water injection layer 60. The purification device 72 of the injection facility 70 has the same configuration as the purification device 32 in the first embodiment.

  Moreover, the pumping well 80 has the tip reaching the contaminated layer G2, and can pump the groundwater of the contaminated layer G2 from a strainer (not shown) formed at the tip.

  Thereby, the injection liquid produced | generated with the purification apparatus 32 is inject | poured into the water injection layer 60 from the water injection well 74, and osmose | permeates the inside of the water injection layer 60 to a horizontal direction. Then, it penetrates from the water injection layer 60 into the contaminated layer G2 to purify the pollutant E. Thereafter, the water is pumped from the pumping well 80 together with the groundwater.

  FIG. 6A shows a plan view showing the arrangement of the water injection well 74, the pumping well 80, and the water injection layer 60. The water injection layer 60 is formed in a planar shape across the plurality of water injection wells 74 and the pumping wells 80.

  In order to form such a water injection layer 60, first, as shown in FIG. 7A, a hole 90 reaching the contaminated layer G2 sandwiched between the clay layers G1 is drilled from the ground surface of the soil G. .

  Next, as shown in FIG. 7B, a hollow discharge pipe 92 is inserted into the pit hole 90, and a high-pressure water flow is directed from the discharge port 92 </ b> A formed in the pipe wall of the discharge pipe 92 toward the hole wall of the pit hole 90. To form a notch GE in the contaminated layer G2.

  Further, as shown in FIG. 7C, the notch GE is cut and extended in the lateral direction. In order to open the notch GE, a fracturing fluid (split fluid) is pumped from the discharge port 92A to the notch GE. The fracturing fluid is water to which a chemical substance used when excavating soil or rock body with water pressure is added. In the present embodiment, the fracturing fluid is a viscous fluid having self-decomposability. Further, in order to promote the purification of the pollutant E, it contains a decomposed substance of the pollutant E. The self-decomposing property is a property that the viscosity decreases with the passage of time, and the fracturing fluid is recovered from the pumping well 80 without stagnation in the soil G due to this property.

  By feeding the fracturing fluid into the cutout GE, the fracturing fluid flows into the contamination layer G2 while opening the portion where the interparticle bonding force of the particles forming the contamination layer G2 is weak, and a planar channel GW is formed. The

  Further, as shown in FIG. 7D, a fracturing fluid mixed with dredged sand or gravel having a particle diameter larger than the particles forming the contaminated layer G2 is discharged from the discharge port 92A to the flow path GW, and this dredged sand or Fill the flow path GW with gravel. Thereby, the water injection layer 60 </ b> A surrounding the pothole 90 is formed.

  As shown in FIG. 8B, the water injection layer 60 </ b> A is formed in a planar shape around the pothole 90. A plurality of holes 90 are drilled at predetermined intervals, and the water injection layer 60 </ b> A is formed for each hole 90 by the above-described steps of FIGS. 7 (B) to (D). Thereby, as shown to FIG. 8 (A), 60A of water injection layers are connected, and the water injection layer 60 shown to FIG. 6 (A), (B) is formed.

  The pothole 90 after forming the water injection layer 60 can be used as the water injection well 74 or the pumping well 80 by inserting a casing.

  In the soil purification system 14 according to the third embodiment, when the pollutant E spreads in a planar shape inside the soil G, the water injection layer 60 can be formed immediately above the pollutant E. For this reason, the pollutant E can be effectively purified.

  Note that the soil purification system 14 according to the third embodiment can be applied not only when the pollutant E spreads in a planar shape but also when it spreads in a deep part of the soil G. Even in such a case, if the water injection layer 60 is formed immediately above the contaminant E, the purification efficiency is high.

[Fourth Embodiment]
As shown in FIG. 9, in the soil purification system 16 according to the fourth embodiment, the water injection layer 110 is formed in a wall shape downward from the ground surface of the soil G. When the wall-shaped water injection layer 110 is viewed from the front, the water injection layer 110 is disposed so as to overlap the pollutant E of the soil G.

  The injection facility 100 includes a purification device 102 and an injection pipe 104 that injects the injection solution generated by the purification device 102 into the water injection layer 110. The injection pipe 104 is laid along the vertical direction inside the water injection layer 110 in order to quickly infiltrate the injection solution into the water injection layer 110. Furthermore, a pumping well 120 is provided on the opposite side of the water injection layer 110 with the pollutant E interposed therebetween.

  In the soil purification system 16 according to the fourth embodiment, the injected solution injected into the water injection layer 110 diffuses into the surface of the water injection layer 110 and penetrates the soil G evenly. For this reason, the injection liquid can pass through the entire part including the contaminant E in the soil G.

  In the first and second embodiments, the water injection layer 20 is formed on the ground surface above the pollutant E as shown in FIGS. 1 and 5, and in the third embodiment, the water injection layer 20 in FIG. As shown in (B), the top of the water injection well 74 is exposed on the ground surface. That is, in the first to third embodiments, it is necessary to perform installation work of the water injection layer 20 and excavation work of the water injection well 74 on the ground surface above the pollutant E.

  On the other hand, in the fourth embodiment, it is not necessary to perform construction on the ground surface above the pollutant E. For this reason, when there is a building above the pollutant E, the soil G can be purified while the building is in service.

  In addition, in the soil purification system 16, although the injection pipe 104 is laid along the up-down direction inside the water injection layer 110, embodiment of this invention is not restricted to this. For example, the injection pipe may be embedded in the lateral direction above the water injection layer 110, or the injection liquid may be poured into the water injection layer 11 without using the injection pipe. Even in this case, the injected liquid penetrates into the water injection layer 110 by gravity.

  Moreover, although groundwater is pumped by the pumping well 120, embodiment of this invention is not restricted to this. For example, the ground surface may be excavated in a groove shape to form a culvert filled with crushed stone, and groundwater may be pumped from the culvert. If a culvert is formed instead of the pumping well 120, the construction of the pumping facility becomes easy.

20, 28, 60, 110 Water injection layer 30, 70, 100 Injection facility 40, 80, 120 Pumping well (pumping facility)
50 Water blocking wall G Soil

Claims (3)

A water injection layer provided in the surface of the soil or in the soil and formed into a planar shape with a material having higher water permeability than the soil;
An injection facility for injecting an injection solution containing a substance for decomposing pollutants into the water injection layer, and infiltrating the injection solution from the water injection layer into the soil;
A soil purification system comprising: a pumping facility for pumping ground water containing the injected liquid from the soil.   The soil purification system according to claim 1, wherein the water injection layer is provided on a surface of the soil, and the pumping equipment is a pumping well.   The soil purification system of Claim 2 with which the water stop wall is provided in the outer peripheral part of the said water injection layer.